Effect of the Conduction Type of Si (111) Substrates on the Performance of GaN MQW LED Epitaxial Films

The present paper prepared a structural epitaxial film of gallium nitride multiple-quantum-well (GaN MQW) blue light-emitting diode (LED) on Si (111) substrates with different conduction types using the metal-organic chemical vapor deposition method. The method prevented the interdiffusion of GaN and Si to achieve high-quality film growth by introducing aluminium nitride (AlN)-interposed layer and rich-Gallium GaN layer with low V/III ratio double buffer layers. Surface analysis shows that the GaN LED epitaxial film on the Si (111) substrate with different conduction types presented an entirely different appearance. The surface roughness of all the samples was less than 3 nm. A much smoother surface of the epitaxial film on the N-type substrate had less roughness, whereas a layered stack surface of the epitaxial film on the P-type substrate had larger surface roughness. The full width at half maximum of the XRD Omega rocking curve with (002) and (102) planes of GaN film grown on the N-type substrate was less than that of the GaN film on the P-type substrate. Furthermore, the film was superior to the samples on the P-type substrate in terms of crystal quality. There was little difference in the peak position of the PL of the epitaxial film on the N-type substrate, but the peak position of the PL of the epitaxial film on the P-type substrate was long and had a large half-peak width. The tensile stress of the GaN film on the P-type substrate was higher. The above results show that the N-type Si (111) substrate with high resistivity is more suitable for the growth of GaN MQW LED epitaxial film.